1. Field of the Invention
The present invention relates to an apparatus to pressurize a pneumatic tire during rotation thereof and, more particularly, the present invention provides such an apparatus mounted externally of the pneumatic tire at a site eccentric to rotation of the tire for utilizing a locus of forces to pressurize air to control the inflation of the tire.
2. Description of the Prior Art
While not so limited, the present invention provides a pneumatic pump constructed for attachment to an air supply valve stem of a pneumatic tire of an automobile or the like, to pressurize and, if desired, control the tire pressure at a predetermined pressure. In U.S. Pat. No. 4,349,064 there is disclosed a tire pump mounted within a tire. A piston of the pump moves radially with respect to the rim. The pump is mounted on the tire rim and is actuated by centrifugal force to draw in and pressurize atmospheric air as the tire rolls along the ground. When the pressure within the tire reaches a pre-set level the air in the tire is recirculated through the pump to prevent the buildup of excessive pressure. Such a system requires permanent attachment of the pump to the rim of the wheel, modification of the wheel structure, and removal of the tire in order to service or replace the pump.
Other known centrifugally-operated pump regulators are described in U.S. Pat. No. 4,570,691 wherein the pump is secured to the wheel rim interiorly of the tire and in U.S. Pat. No. 4,651,792 wherein the pump is secured to the interior of the tire. These pumps suffer from disadvantages similar to those associated with U.S. Pat. No. 4,349,064. Furthermore, all of the aforementioned pumps/regulators operate exclusively on the principal of harnessing and utilizing only centrifugal force, a force which is not cyclic so that the pump must embody a design to operate independent of wheel translation.
In so far as presently known, there is no known mechanical application to utilize the combination of centrifugal and gravitational forces occurring at a location eccentric from an axis of rotation of a body experiencing rolling translation. Such forces resolve to a resultant force that is ever changing during each rotation at all points eccentric from the axis of rotation of a rolling vehicle wheel. Hence, an advantage exists for an apparatus for harnessing and utilizing the locus of forces at a location eccentric from an axis of rotation of a rolling body, particularly, a vehicle wheel or the like. Such an apparatus can be mounted to a vehicle wheel and advantageously used, inter alia, to power a pump for pressuring and, if desired, regulating the pressure of a pneumatic vehicle tire.
The forces driving this kind of pump are forces that are normally imparted to on the valve of a rotating tire while a vehicle is in motion. The variability of these force during each complete revolution of the wheel are sufficient to impart the reciprocal motion to a piston type pump for vehicle speeds above a certain minimum speed of about 10 miles per hour, for example. The pressurizing of a low volume of air to a predetermined pressure by the pump can be controlled by diverse means such as a pressure control valve to maintain the tire pressure at a desired level required by present day standards. The input of air pressure from the pump may, if desired, be applied in opposition to the pneumatic pressure of the tire such that the tire pressure is increased or by a reverse flow of air, a small volume of air can be exhausted through a pump to the atmosphere. In this mode of operation, the tire pressure is reduced incrementally according to the magnitude of pressurization of air by the pump. This enables a pump construction to achieve and maintain a predetermined tire pressure according to operating parameters for the tire such as radius rotation for the tire, desired tire pressure and air pressure volume of the tire.
There are significant benefits from such a system to the owner of a vehicle whether it is an automobile, motorcycle or truck. First, the maintenance of the correct tire pressure will protect a tire from over or under inflation and result in its longer life for the tire. Second, this system, when applied to all wheels of a vehicle, will maintain even and balanced inflation in all tires and allow for easy and safe handling of the vehicle. Incorrect tracking of the vehicle due to uneven tire pressure will be eliminated. Tire wear will be improved relatively constant and balanced to all tires over their useful life. Lastly, the maintenance of correct tire pressure will increase gas mileage of the vehicle and provide a further saving to the operator. It has been reported by the Federal Department of Transportation that 2 million gallons of gasoline a day could be saved if all motor vehicles on the road were to operate with correct tire pressures.
It is an object of the present invention to provide apparatus for harnessing and utilizing forces at a location eccentric from the axis of rotation of a vehicle wheel for pressurizing and regulating the air pressure of a pneumatic tire carried by the wheel.
It is a further object of the present invention to provide a readily accessible pneumatic tire pump/regulator which can be manufactured for incorporation as part of or for releasably attachment to existing valve stem structure for a pneumatic tire.
It is a further object of the present invention to provide a pneumatic tire pump/regulator requiring no modification of either the vehicle wheel or the pneumatic tire.
Still other objects and advantages of the present invention will become apparent in light of the attache drawings and written description of the invention presented hereinbelow.